Anti-Two Block System
MAINTENANCE
This crane is equipped with an anti-two block system for both main boom head and jib
which sounds a horn (when in the "on" position) and lights a light when a two-blocking
condition is imminent. If equipped with control disconnects, it will also disengage the
hydraulic functions. Verify that the two-blocking system is functioning properly by
performing the following procedure.
Check anti-two block switch(es) and freedom of (item 2) chain-hung counterweight (item 1)
as shown on main boom head in photo below or in similar application on jib. Check the
plug and socket connection at boom head and on lib, if erected and reeved, for connection.
The jib connector must be plugged into the boom head receptacle. Check system
indication (and shut-off, if so equipped) by manually lifting chain hung counterweight( s). A
warning light should come on, horn in “on” position should sound, and (if so equipped) shut-
off system should disconnect controls. Check entire length of cable and cable reel for
evidence of damage. Check spring loaded cable reel. Ensure it has spring tension and is
free to rotate. Check cab control unit. If the crane is equipped with control linkage
disconnect, perform the following checks, also.
367P/N 12261-683 REVISED: January 2015
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